Reduction of nitric oxide and DNA/RNA oxidation products are associated with active disease in systemic lupus erythematosus patients.

The aims of the present study were to evaluate biomarkers of oxidative and nitrosative stress in systemic lupus erythematosus (SLE) patients, in particular products of DNA/RNA oxidative damage and their correlation with disease activity. This study included 188 controls and 203 patients; 153 with inactive SLE (SLEDAI<6) and 50 with active SLE (SLEDAI6) without renal impairment. Oxidative stress was assessed by tert-butyl hydroperoxideinitiated by chemiluminescence, advanced oxidation protein products (AOPP), total radical-trapping antioxidant parameter (TRAP), nitric oxide metabolites (NOx), and DNA/RNA oxidation products. Patients with SLE showed increased oxidative stress, as demonstrated by the augmentation of lipid hydroperoxides (p<0.0001) and AOPP (p<0.001) and reduced total antioxidant capacity (p<0.0001), without differences between patients with active disease and in remission. NOx levels and DNA/RNA oxidation products were inversely and independently associated with disease activity (p<0.0001 and p=0.021, respectively), regardless of BMI and prednisone use. The linear regression analysis showed that about 5% of the SLEDAI score can be explained by the levels of DNA/RNA oxidation products (r(2):0.051; p=0.002) and about 9% of this score by the levels of NOx (r(2):0.091; p<0.0001). This study provides evidence for an inverse association between serum NOx levels and DNA/RNA oxidation products and SLE disease activity, suggesting that oxidative/nitrosative stress markers may be useful in evaluating SLE disease activity and progression of the disease.